In FFII, Ultima was a piece of suck that did maybe 800 damage while your Fire spell was probably doing around 1500. :P
Ultima was the most powerful spell when I played FFII.
Ultima in II can either be the strongest spell in the game or the weakest. I've had it doing 3-4000 while flare was doing no more than 2000, but before I knew how it worked, it sucked.